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  1. AU="Kivala, Milan"
  2. AU="Salafia, O S"
  3. AU="Taghavi, Fouad J"
  4. AU="Xiao, Jun-Hua"
  5. AU="Vee Sin Lee, Peter"
  6. AU="Zhu, Yali"
  7. AU="Jiang-Qi Liu"
  8. AU="Moores, Roxanna"

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  1. Article ; Online: Indenoannulated Tridecacyclene: An All-Carbon Seven-Stage Redox-Amphoter.

    Misselwitz, Erik / Spengler, Jonas / Rominger, Frank / Kivala, Milan

    Chemistry (Weinheim an der Bergstrasse, Germany)

    2024  , Page(s) e202400696

    Abstract: We disclose an indenoannulated tridecacyclene comprising a central cyclooctatetraene moiety with multiple adjacent pentagonal rings which is accessible in a concise synthetic sequence. The saddle-shaped geometry of the non-benzenoid polycyclic scaffold ... ...

    Abstract We disclose an indenoannulated tridecacyclene comprising a central cyclooctatetraene moiety with multiple adjacent pentagonal rings which is accessible in a concise synthetic sequence. The saddle-shaped geometry of the non-benzenoid polycyclic scaffold and its unique packing behavior in the solid state were characterized by X-ray crystallography. In electrochemical studies, the compound undergoes seven reversible redox events comprising five reductions and two oxidations. The dicationic and dianionic species obtained by chemical oxidation and reduction, respectively, were characterized spectroscopically in solution. Density functional theory calculations were applied to provide insights into aromaticity evolution in the respective charged species, highlighting the beneficial effect of the non-benzenoid moieties on charge stabilization.
    Language English
    Publishing date 2024-04-02
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1478547-X
    ISSN 1521-3765 ; 0947-6539
    ISSN (online) 1521-3765
    ISSN 0947-6539
    DOI 10.1002/chem.202400696
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  2. Article ; Online: Helically Chiral π-Expanded Azocines Through Regioselective Beckmann Rearrangement and Their Charged States.

    Borstelmann, Jan / Schneider, Lars / Rominger, Frank / Deschler, Felix / Kivala, Milan

    Angewandte Chemie (International ed. in English)

    2024  , Page(s) e202405570

    Abstract: We report a synthetic approach to p-expanded [6]helicenes incorporating tropone and azocine units in combination with a 5-membered ring, which exhibit intriguing structural, electronic, and chiroptical properties. The regioselective Beckmann ... ...

    Abstract We report a synthetic approach to p-expanded [6]helicenes incorporating tropone and azocine units in combination with a 5-membered ring, which exhibit intriguing structural, electronic, and chiroptical properties. The regioselective Beckmann rearrangement allows the isolation of helical scaffolds containing 8-membered lactam, azocine, and amine units. As shown by X-ray crystallographic analysis, the incorporation of tropone or azocine units leads to highly distorted [6]helicene moieties, with distinct packing motifs in the solid state. The compounds exhibit promising optoelectronic properties with considerable photoluminescence quantum yields and tunable emission wavelengths depending on the relative position of the nitrogen center within the polycyclic framework. Separation of the enantiomers by chiral high-performance liquid chromatography (HPLC) allowed characterization of their chiroptical properties by circular dichroism (CD) and circularly polarized luminescence (CPL) spectroscopy. The azocine compounds feature manifold redox chemistry, allowing for the characterization of the corresponding radical anions and cations as well as the dications and dianions, with near-infrared (NIR) absorption bands extending beyond 3000 nm. Detailed theoretical studies provided insights into the aromaticity evolution upon reduction and oxidation, suggesting that the steric strain prevents the azocine unit from undergoing aromatization, while the indene moiety dominates the observed redox chemistry.
    Language English
    Publishing date 2024-05-08
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2011836-3
    ISSN 1521-3773 ; 1433-7851
    ISSN (online) 1521-3773
    ISSN 1433-7851
    DOI 10.1002/anie.202405570
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  3. Article ; Online: A Negatively Curved π-Expanded Pyracylene Comprising a Tropylium Cation.

    Borstelmann, Jan / Bergner, John / Rominger, Frank / Kivala, Milan

    Angewandte Chemie (International ed. in English)

    2023  Volume 62, Issue 46, Page(s) e202312740

    Abstract: We disclose π-expanded pyracylenes and their cationic species comprising 7-membered rings. The compounds were synthesized by stepwise oxidative cyclodehydrogenation to monitor the effect of successive cyclization on the structural and optoelectronic ... ...

    Abstract We disclose π-expanded pyracylenes and their cationic species comprising 7-membered rings. The compounds were synthesized by stepwise oxidative cyclodehydrogenation to monitor the effect of successive cyclization on the structural and optoelectronic properties. As shown by X-ray crystallography, the complete cyclization leads to a boat-shaped scaffold featuring negative curvature provided by the 7-membered ring. The embedded tropone unit enabled the convenient generation of a stabilized tropylium cation, showing bathochromically shifted absorption bands reaching into the near-infrared region beyond 1000 nm. The altered structural features, supported by theoretical calculations, point towards the positively charged 7-membered ring having aromatic character.
    Language English
    Publishing date 2023-10-12
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2011836-3
    ISSN 1521-3773 ; 1433-7851
    ISSN (online) 1521-3773
    ISSN 1433-7851
    DOI 10.1002/anie.202312740
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  4. Article ; Online: Unveiling the Multielectron Acceptor Properties of π-Expanded Pyracylene: Reversible Boat to Chair Conversion.

    Zhu, Yikun / Borstelmann, Jan / Bertleff, Oliver / Bergner, John / Wei, Zheng / Neiss, Christian / Görling, Andreas / Kivala, Milan / Petrukhina, Marina A

    Journal of the American Chemical Society

    2024  Volume 146, Issue 21, Page(s) 14715–14723

    Abstract: In this work, the chemical reduction of a hybrid pyracylene-hexa- ...

    Abstract In this work, the chemical reduction of a hybrid pyracylene-hexa-
    Language English
    Publishing date 2024-05-13
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3155-0
    ISSN 1520-5126 ; 0002-7863
    ISSN (online) 1520-5126
    ISSN 0002-7863
    DOI 10.1021/jacs.4c02314
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  5. Article ; Online: Inducing Curvature to Pyracylene upon π-Expansion.

    Bergner, John / Walla, Christian / Rominger, Frank / Dreuw, Andreas / Kivala, Milan

    Chemistry (Weinheim an der Bergstrasse, Germany)

    2022  Volume 28, Issue 47, Page(s) e202201554

    Abstract: We disclose a successive π-expansion of pyracylene towards boat-shaped polycyclic scaffolds. The unique structural features of the resulting compounds were revealed by X-ray crystallographic analysis. Depending on the extent of π-expansion the compounds ... ...

    Abstract We disclose a successive π-expansion of pyracylene towards boat-shaped polycyclic scaffolds. The unique structural features of the resulting compounds were revealed by X-ray crystallographic analysis. Depending on the extent of π-expansion the compounds display intense bathochromically shifted absorption bands in their UV/Vis spectra and are prone to several redox events as documented by cyclic voltammetry. The experimental observations are in line with the computational studies based on density functional theory, suggesting progressive narrowing of the HOMO-LUMO gap and distinct evolution of the electronic structure and aromaticity.
    Language English
    Publishing date 2022-07-06
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1478547-X
    ISSN 1521-3765 ; 0947-6539
    ISSN (online) 1521-3765
    ISSN 0947-6539
    DOI 10.1002/chem.202201554
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  6. Article ; Online: A Chiral Molecular Cage Comprising Diethynylallenes and N-Heterotriangulenes for Enantioselective Recognition.

    Míguez-Lago, Sandra / Gliemann, Bettina D / Kivala, Milan / Cid, María Magdalena

    Chemistry (Weinheim an der Bergstrasse, Germany)

    2021  Volume 27, Issue 53, Page(s) 13352–13357

    Abstract: Chirality, a characteristic tool of molecular recognition in nature, is often a complement of redox active systems. Scientists, in their eagerness to mimic such sophistication, have designed numerous chiral systems based on molecular entities with ... ...

    Abstract Chirality, a characteristic tool of molecular recognition in nature, is often a complement of redox active systems. Scientists, in their eagerness to mimic such sophistication, have designed numerous chiral systems based on molecular entities with cavities, such as macrocycles and cages. In an attempt to combine chirality and redox-active species, in this contribution we report the synthesis and detailed characterization of a chiral shape-persistent molecular cage based on the combination of enantiopure diethynylallenes and electron-rich bridged triarylamines, also known as N-heterotriangulenes. Its ability for chiral recognition in solution was revealed through UV/vis titrations with enantiopure helicenes.
    MeSH term(s) Molecular Structure ; Stereoisomerism
    Language English
    Publishing date 2021-08-12
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1478547-X
    ISSN 1521-3765 ; 0947-6539
    ISSN (online) 1521-3765
    ISSN 0947-6539
    DOI 10.1002/chem.202101801
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  7. Article: Self-Assembly of a Triphenylene-Based Electron Donor Molecule on Graphene: Structural and Electronic Properties.

    de la Rie, Joris / Enache, Mihaela / Wang, Qiankun / Lu, Wenbo / Kivala, Milan / Stöhr, Meike

    The journal of physical chemistry. C, Nanomaterials and interfaces

    2022  Volume 126, Issue 23, Page(s) 9855–9861

    Abstract: In this study, we report on the self-assembly of the organic electron donor 2,3,6,7,10,11-hexamethoxytriphenylene (HAT) on graphene grown epitaxially on Ir(111). Using scanning tunneling microscopy and low-energy electron diffraction, we find that a ... ...

    Abstract In this study, we report on the self-assembly of the organic electron donor 2,3,6,7,10,11-hexamethoxytriphenylene (HAT) on graphene grown epitaxially on Ir(111). Using scanning tunneling microscopy and low-energy electron diffraction, we find that a monolayer of HAT assembles in a commensurate close-packed hexagonal network on graphene/Ir(111). X-ray and ultraviolet photoelectron spectroscopy measurements indicate that no charge transfer between the HAT molecules and the graphene/Ir(111) substrate takes place, while the work function decreases slightly. This demonstrates that the HAT/graphene interface is weakly interacting. The fact that the molecules nonetheless form a commensurate network deviates from what is established for adsorption of organic molecules on metallic substrates where commensurate overlayers are mainly observed for strongly interacting systems.
    Language English
    Publishing date 2022-06-01
    Publishing country United States
    Document type Journal Article
    ISSN 1932-7447
    ISSN 1932-7447
    DOI 10.1021/acs.jpcc.1c10266
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  8. Article ; Online: A Symmetrically π-Expanded Carbazole Incorporating Fluoranthene Moieties.

    Vogel, Alexander / Schreyer, Till / Bergner, John / Rominger, Frank / Oeser, Thomas / Kivala, Milan

    Chemistry (Weinheim an der Bergstrasse, Germany)

    2022  Volume 28, Issue 67, Page(s) e202201424

    Abstract: A novel doubly cyclopentannulated carbazole which is accessible through a successive π-expansion of di(1-naphthylamine) is disclosed. The carbazole moiety is generated in the final step through intramolecular oxidative coupling. The π-expansion of ... ...

    Abstract A novel doubly cyclopentannulated carbazole which is accessible through a successive π-expansion of di(1-naphthylamine) is disclosed. The carbazole moiety is generated in the final step through intramolecular oxidative coupling. The π-expansion of carbazole resulted in strongly altered optoelectronic and electrochemical properties. The solid-state structure features an interesting packing motif with alternating face-to-face π⋅⋅⋅π and edge-to-face C-H⋅⋅⋅π interactions. The experimental findings were corroborated by theoretical calculations.
    Language English
    Publishing date 2022-10-05
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1478547-X
    ISSN 1521-3765 ; 0947-6539
    ISSN (online) 1521-3765
    ISSN 0947-6539
    DOI 10.1002/chem.202201424
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  9. Article ; Online: Silver cation tagged on 5,7,12,14-tetraphenyl-6,13-diazapentacene and its dihydro-form.

    Kinzelmann, Marina / Oschwald, Johannes / Elsen, Holger / Warmbrunn, Vera / Hauschild, Miriam / Harder, Sjoerd / Kivala, Milan / Drewello, Thomas

    Physical chemistry chemical physics : PCCP

    2023  Volume 25, Issue 22, Page(s) 15382–15390

    Abstract: The attachment of silver(I) cations to 5,7,12,14-tetraphenyl-6,13-diazapentacene and its reduced dihydro-form has been studied by electrospray ionization mass spectrometry (ESI-MS). The structure elucidation of the ... ...

    Abstract The attachment of silver(I) cations to 5,7,12,14-tetraphenyl-6,13-diazapentacene and its reduced dihydro-form has been studied by electrospray ionization mass spectrometry (ESI-MS). The structure elucidation of the Ag
    Language English
    Publishing date 2023-06-07
    Publishing country England
    Document type Journal Article
    ZDB-ID 1476244-4
    ISSN 1463-9084 ; 1463-9076
    ISSN (online) 1463-9084
    ISSN 1463-9076
    DOI 10.1039/d2cp05929k
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  10. Article ; Online: Isomeric Dithienophosphepines: The Impact of Ring Fusion on Electronic and Structural Properties.

    Padberg, Kevin / Ascherl, Johannes D R / Hampel, Frank / Kivala, Milan

    Chemistry (Weinheim an der Bergstrasse, Germany)

    2020  Volume 26, Issue 16, Page(s) 3474–3478

    Abstract: The synthesis and extensive experimental (X-ray crystallography, UV/Vis spectroscopy, cyclic voltammetry) and theoretical (DFT calculations) characterization of two isomeric dithieno[b,f]phosphepines (DTPs) are presented herein. The relative orientation ... ...

    Abstract The synthesis and extensive experimental (X-ray crystallography, UV/Vis spectroscopy, cyclic voltammetry) and theoretical (DFT calculations) characterization of two isomeric dithieno[b,f]phosphepines (DTPs) are presented herein. The relative orientation of the phosphepine and the thiophene moieties has a decisive impact on the electronic and structural properties of these compounds. Moreover, the thiophene units allow for a facile subsequent functionalization through direct Pd-catalyzed C-H coupling, which renders DTPs highly promising building blocks for organophosphorus functional materials.
    Language English
    Publishing date 2020-01-30
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1478547-X
    ISSN 1521-3765 ; 0947-6539
    ISSN (online) 1521-3765
    ISSN 0947-6539
    DOI 10.1002/chem.201905429
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